Magnetoelectronic devices, spin electronic devices and spintronic devices are synonymous terms for devices that use effects predominantly caused by electron spin. Spintronic devices are electronic devices that utilize the correlation between the charge and spin of electrons to bring about spin-dependent electronic functionality. Spintronic effects can be used in numerous information devices, and provide non-volatile, reliable, radiation resistant, and high-density data storage and retrieval. The numerous spintronic devices include, but are not limited to, magnetic random access memory (MRAM), magnetic sensors, spin transistors, spin valves and read/write heads for disk drives.
Ferromagnetic semiconductor materials are of considerable interest as spin injectors for spintronic devices. Dilute magnetic semiconductors, such as manganese-doped II-VI and III-V semiconductors, which are obtained by doping magnetic impurities into host semiconductors, have become of considerable interest for their ferromagnetic properties. However, a major drawback for conventional III-V and II-VI semiconductors doped with magnetic ions is that generally the measured Curie points are well below room temperature. Thus, production of such ferromagnetic semiconductor devices has not been commercially successful. Cobalt-doped titanium oxide anatase has been reported to have a Curie point above room temperature. However, growth of this material has been achieved on oxide substrates such as strontium titanate and lanthium aluminate substrates. For large-scale commercial viability such material should be integrated on conventional monocrystalline semiconductor substrates such as silicon, germanium, or gallium arsenide.
Accordingly, there is a need for a ferromagnetic semiconductor structure having a Curie point above room temperature and a method for making such a structure. There is also a need for a ferromagnetic semiconductor structure that is formed overlying a monocrystalline semiconductor substrate and a method for making such a structure. Other desirable features and characteristics of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.